Peroxymonosulfate Concentration Research Articles

CoFe2O4/WS2 as a highly active heterogeneous catalyst for the efficient degradation of sulfathiazole by activation of peroxymonosulfate

In this study, MFe2O4/WS2 (M = Co, Cu, Mn, Ni) catalysts were synthesized to activate peroxymonosulfate (PMS) for sulfathiazole (STZ) degradation by decorating with WS2 on the surface of a series of spinel-type transition metal oxides. It was found that the CoFe2O4/WS2/PMS exhibited a greater ability to degrade sulfathiazole (STZ) than other systems. More specifically, the catalyst facilitated Fe3+/Fe2+ recycling to activate PMS efficiently and maintained synergies between CoFe2O4 and WS2 to degrade pollutants. The CoFe2O4/WS2 dosage, PMS concentration, solution pH, inorganic anions, and natural organic matter, which could affect the catalytic efficiency, were inspected. The experimental results manifested that the catalyst displayed outstanding performance in the pH range from 5 to 9. Besides, electron paramagnetic resonance spectroscopy and radical quenching experiments confirmed the presence of HO•, SO4•−, O2•−, and 1O2. Based on detected intermediates, the plausible degradation pathway of STZ was proposed.

A new magnetic heterogeneous catalyst for fast degradation of rhodamine B by peroxymonosulfate oxidation: Monodisperse-porous and Fe3O4 incorporated manganese oxide microspheres

A new synthetic method, “staged shape templating decomposition” suitable for transition or rare-earth metal oxide microspheres was developed for obtaining magnetic, uniform and porous manganese oxide (MagMnOx) microspheres. The microspheres 4.7 μm in size were obtained with a specific surface area of 45.5 m2 g−1. Fe3O4, Mn5O8, MnO2 and Mn2O3 phases were shown by X-ray diffraction spectroscopy. Mn2+, Mn3+ and Mn4+ states were observed on the surface by X-ray photoelectron spectroscopy. Catalase-like and oxidase-like activities of MagMnOx microspheres were explained by coexistence of Mn and Fe crystallites in a mesoporous structure with a sufficiently large surface area and a particle interior with large mesopores facilitating substrate diffusion. The maximum substate consumption rates for catalase-like and peroxidase-like activities were determined as 15.6 mM/min and 20.3 μM/min, respectively. By considering their ROS generation ability, MagMnOx microspheres were evaluated as a heterogeneous catalyst for rhodamine B (Rh B) removal via peroxymonosulfate (PMS) activation. Rh B was removed in the periods shorter than 15 min via chemical degradation with a limited physical adsorption. Superoxide anion (O2−●) and singlet oxygen (1O2●) radicals generated by MagMnOx-PMS system were responsible for degradation of Rh B. The highest apparent first order rate constant for Rh B degradation was calculated as 0.5771 min−1. The apparent first order rate constant increased with increasing MagMnOx and PMS concentrations and decreasing initial Rh B concentration. Rh B was almost completely removed in each of five recycling runs and only lower than 1.5 % w/w of Fe and Mn contents of MagMnOx microspheres were leached over five recycling runs. The catalyst with large particle size, resistant to agglomeration exhibited high removal rate, low dye adsorption, high magnetization, and high reusability for Rh B removal via peroxymonosulfate activation.

Mechanism exploration in tetracycline degradation by Ni-Fe layered double hydroxide-biochar/peroxymonosulfate system: Nonradical-dominated oxidation process

Metal-based materials are widely regarded as promising catalysts for activating peroxymonosulfate (PMS) to remove refractory organic contaminants with high efficiency. In our study, Ni-Fe layered double hydroxide (LDH)-biochar (BC) composite-induced PMS-based advanced oxidation process (AOP) was utilized to elucidate the degradation of tetracycline hydrochloride (TCH). In Ni-Fe LDH-BC/PMS system, more than 99% TCH (45 μM) could be removed effectively at low doses of oxidant (PMS, 0.10 mM) and catalyst (Ni-Fe LDH-BC, 0.10 g/L) addition within 80 min. Besides, the Ni-Fe LDH-BC/PMS system showed high resistance to some inorganic anions, and the Ni-Fe LDH-BC composite possessed excellent reusability in the degradation of TCH (>99% in four cyclic experiments). The reaction mechanisms were investigated via electron paramagnetic resonance detection, chemical quenching tests, probe experiments, and electrochemical measurements. These results indicated that the electron-shuttle mechanism played the dominant role in the removal of TCH. It is worth noting that determination of PMS concentration can reflect the reliability of quenching experiments. In the Ni-Fe LDH-BC composite, BC could not only improve the dispersion of Ni-Fe LDH, but also increase the conductivity of Ni-Fe LDH. Overall, a successful modification strategy was proposed in our study to improve the catalytic property of Ni-Fe LDH, and reaction mechanisms of TCH degradation were discussed deeply and comprehensively.

In situ growth of CuO on porous geopolymer spheres as green catalysts for enhanced peroxymonosulfate‐activated degradation of Orange I

AbstractIn this study, in situ growth of CuO on the surface of porous geopolymer catalyst spheres (GC) was prepared through a simple method for the activation of peroxymonosulfate (PMS) to degrade Orange I (OI) in water. GC‐0.01 exhibited an excellent performance with more than 95% degradation of OI within 30 min. The effects of PMS concentrations, catalyst dosage, Cl−, HCO3−, and humic acid (HA) on OI degradation in the GC‐0.01/PMS system were systematically investigated. The study of the mechanism showed that PMS combined with the catalyst to generate complexes on the surface of the spheres, which could degrade OI through an electron transfer pathway. In addition, a variety of reactive oxygen species, mainly 1O2, were also present in the GC‐0.01/PMS system, which could also degrade OI. This work provides new insight into the application of oxide‐modified geopolymers in the activation of PMS for water purification applications.

Degradation of Ciprofloxacin in Water by Magnetic-Graphene-Oxide-Activated Peroxymonosulfate.

Antibiotics are extensively applied in the pharmaceutical industry, while posing a tremendous hazard to the ecosystem and human health. In this study, the degradation performance of ciprofloxacin (CIP), one of the typical contaminants of antibiotics, in an oxidation system of peroxymonosulfate (PMS) activated by magnetic graphene oxide (MGO) was investigated. The effects of the MGO dosage, PMS concentration and pH on the degradation of CIP were evaluated, and under the optimal treatment conditions, the CIP degradation rate was up to 96.5% with a TOC removal rate of 63.4%. A kinetic model of pseudo-secondary adsorption indicated that it involves an adsorption process with progressively intensified chemical reactions. Furthermore, the MGO exhibited excellent recyclability and stability, maintaining strong catalytic activity after three regenerative cycles, with a CIP removal rate of 87.0%. EPR and LC-MS experiments suggested that •OH and SO4-• generated in the MGO/PMS system served as the main reactants contributing to the decomposition of the CIP, whereby the CIP molecule was effectively destroyed to produce other organic intermediates. Results of this study indicate that organic pollutants in the aqueous environment can be effectively removed in the MGO/PMS system, in which MGO has excellent catalytic activity and stabilization for being recycled to avoid secondary pollution, with definite research value and application prospects in the field of water treatment.

Degradation of phenylarsonic acid in phenylarsenic chemical warfare agents by Fe-modified CNT electroactive filter activating peroxymonosulfate: Performance and mechanism

Phenylarsonic acid (PAA) is a major organic arsenic contaminant in abandoned arsenic-based chemical weapons areas, and poses threats to the water environment due to potential arsenic pollution; However, relevant remediation methods are lacking. In this study, a Fe-modified carbon nanotube (CNT) electroactive filter was developed for peroxymonosulfate (PMS) activation towards PAA decontamination. The developed system can realise synchronous adsorption and oxidation of PAA (85.6 %) with PMS (1.5 mM) under electric field assistance (-1 V). Radicals (SO4•– and HO•) and non-radicals (1O2) contributed to PAA degradation and the formation of As (V). The preferable PAA degradation efficiency stemmed from facilitated Fe (II)/Fe (III) redox cycles with applied electric field assistance. Secondary inorganic arsenic could also be immobilised as FeOAs bonds on the Fe-modified CNT filter. Additionally, PAA degradation pathways were proposed based on density functional theory (DFT) and intermediate identification. The system efficacy was also evaluated by regulating the critical operational parameters (applied voltage, flow rate, PMS concentration, pH and co-existing anions) and using complicated matrices (tap water and lake water). Our findings provide a new solution for PAA remediation and simultaneous immobilisation of secondary inorganic arsenic by combining membrane, PMS activation and electrochemical methods.

Continuous flow degradation of Orange II by a dandelion-like NiCo2O4/NF activated peroxymonosulfate in a fixed-bed system

A novel dandelion-like catalyst, nickel foam supported NiCo2O4 (NiCo2O4/NF), was successfully synthesized and applied to the activation of peroxymonosulfate (PMS) in a fixed bed system for the degradation of Orange II (OII). The physicochemical properties of synthesis catalysts were identified by various characterization methods (SEM, EDS, XRD and XPS), revealing that the dandelion-like NiCo2O4 nanosheets were evenly distributed on the surface of NF. NiCo2O4/NF-250 showed excellent catalytic performance at a hydrothermal reaction time of 8 h, urea/metal ratio of 10:1, and Co/Ni concentration of 10 mM/5 mM. When PMS concentration was 5 mM, reaction temperature was 50 ℃, pH was 7.5, space velocity was 0.236 min−1, the conversion ratios of OII, PMS and COD were 99.8 %, 71.3 %, and 71.4 % at 240 min, respectively. In particular, NiCo2O4/NF still could reach 99.9 % OII conversion and 64.4 % COD conversion in the third cycle. DFT calculations implied that NiCo2O4/NF had excellent PMS activation performance.

Removal of polyethylene terephthalate plastics waste via Co–CeO2 photocatalyst–activated peroxymonosulfate strategy

Polyethylene terephthalate (PET) plastic, widely used for packaging owing to its excellent properties, has become a major contributor to plastic waste, for which satisfactory recycling and upgrading treatment technologies are lacking. In this study, Co-doped CeO2 was used as a photocatalyst to degrade PET plastics in water, and PET degradation was measured according to the weight loss rate. Peroxymonosulfate (PMS) addition to the photocatalytic system enabled the degradation of 53.82 ± 4.48 % of PET plastics, highlighting the excellent PET plastic degradation capability of the photocatalytic PMS system. The study investigated the effects of the catalyst-to-plastic ratio, PMS concentration, initial pH, inorganic anions, humic acid concentration, and hydrogen peroxide (H2O2) addition on the catalytic oxidation system. Contrast experiments revealed that H2O2 addition to the photocatalysis/PMS oxidation system further improved the PET plastic degradation efficiency (91.61 ± 1.50 %). Liquid product analysis, electron paramagnetic resonance, and free radical quenching experiments confirmed that SO4− played the most significant role in PET degradation. Finally, a possible mechanism for the degradation of PET plastics in water using the photocatalysis/PMS oxidation system was proposed.

Preparation and performance of FeCo bimetallic organic frameworks with super adsorption and excellent peroxymonosulfate activation for tetracycline removal

As bifunctional materials for adsorption and peroxymonosulfate (PMS) activation, iron − cobalt bimetallic organic frameworks (FeCo − MOF) were successfully fabricated via a facile method at room temperature, and characterized by XRD, SEM, TEM, XPS, TGA, BET and FTIR. Due to the high specific surface area and electrostatic interaction, FeCo − MOF showed excellent adsorption capacity. 30 mg of FeCo − MOF can adsorb 87.5 % of tetracycline (TC) in a 100 mL aqueous solution (70 mg/L). The adsorption data are well fitted by the Langmuir model and pseudo − second − order adsorption kinetics, indicating the TC capture probably was monolayer molecular adsorption and chemisorption. Meanwhile, FeCo − MOF/PMS had the outstanding catalytic activity for TC degradation via PMS activation. 10 mg of FeCo − MOF can remove 91 % of TC within 5 min in a 100 mL aqueous solution (20 mg/L) with PMS (0.1 mmol·L−1). Quenching experiments showed that •OH, SO4•−, O2•− and 1O2 all participate in the TC degradation. The effects of PMS concentration, pH value, reaction temperature on TC degradation were investigated. Although the coexisting inorganic anions and small molecule acids inhibited the catalytic performance of FeCo − MOF/PMS, the TC removal rates were still greater than 80 %, indicating the FeCo − MOF/PMS system has a strong anti − interference ability to complex water environments. In addition, the complete degradation of various pollutants, including TC, methylene orange (MO) and methyl blue (MB), and TC degradation in different water bodies confirmed the wide applicability of the FeCo − MOF/PMS system.

Rice husk–based pyrogenic carbonaceous material efficiently promoted peroxymonosulfate activation toward the non-radical pathway for the degradation of pharmaceuticals in water

Pristine pyrogenic carbonaceous material (BRH) obtained from rice husk and modified with FeCl3 (BRH-FeCl3) were prepared and explored as carbocatalysts for the activation of peroxymonosulfate (PMS) to degrade a model pharmaceutical (acetaminophen, ACE) in water. The BRH-FeCl3/PMS system removed the pharmaceutical faster than the BRH/PMS. This is explained because in BRH-FeCl3, compared to BRH, the modification (iron played a role as a structuring agent mainly) increased the average pore diameter and the presence of functional groups such as -COO−, -Si–O−, or oxygen vacancies, which allowed to remove the pollutant through an adsorption process and significant carbocatalytic degradation. BRH-FeCl3 was reusable during four cycles and had a higher efficiency for activating PMS than another inorganic peroxide (peroxydisulfate, PDS). The effects of BRH-FeCl3 and PMS concentrations were evaluated and optimized through an experimental design, maximizing the ACE degradation. In the optimized system, a non-radical pathway (i.e., the action of singlet oxygen, from the interaction of PMS with defects and/or -COO−/-Si–O− moieties on the BRH-FeCl3) was found. The BRH-FeCl3/PMS system generated only one primary degradation product that was more susceptible to biodegradation and less active against living organisms than ACE. Also, the BRH-FeCl3/PMS system induced partial removals of chemical oxygen demand and dissolved organic carbon. Furthermore, the carbocatalytic system eliminated ACE in a wide pH range and in simulated urine, having a low-moderate electric energy consumption, indicating the feasibility of the carbocatalytic process to treat water polluted with pharmaceuticals.

Removal of refractory organic matter from landfill-contaminated groundwater by a permeable reactive barrier coupled with an Fe0/PMS advanced oxidation system

Advanced oxidation technology based on peroxymonosulfate (PMS) has attracted much attention because of its good degradation and even mineralization of refractory organic matter, but it is less used in the removal of refractory organic matter from landfill-contaminated groundwater (CGW). In this study, an Fe0/PMS advanced oxidation system-based permeable reactive barrier (Fe0/PMS-PRB) has been employed to remove refractory organic matter from landfill leachate CGW. The results show that the Fe0/PMS system offers a significantly higher removal efficiency of organic matter, especially humus, from CGW than other control systems. The main active oxygen species are SO4•─ and HO•, which can facilitate electron-transfer, carbonylation, electrophilic addition, decarboxylation, and other pathways to effectively degrade various refractory organic substances (e.g., bisphenol A, diclofenac acid, and ciprofloxacin). The pseudo-first-order reaction rates reached 0.1083, 0.3030, and 0.0641 min−1, respectively, effectively reducing the bio-toxicity of the effluent. Based on observations by scanning electron microscopy, X-ray diffraction analysis, and X-ray photoelectron spectroscopy, a reaction mechanism was proposed, which involves homogeneous oxidation, heterogeneous oxidation, adsorption, and precipitation of Fe0. In long-term seepage tests, under conditions of an Fe0 loading of 0.7 g, a PMS concentration of 0.8 mm, and a hydraulic retention time of 15 min, after running for 10 pore volumes, the removal extents of aromatic organic matter and total organic carbon from the CGW by the Fe0/PMS-PRB reached 79.01 % and 68.25 %, respectively. Therefore, Fe0/PMS-PRB can effectively remove refractory organic matter from CGW and has good application prospects.

CeO2@LDH decorated 3D porous module with mortise-tenon structure: Activation of peroxymonosulfate for ultrafast removal of tetracycline

Constructing a robust catalytic module with lower energy consumption, fast liquid transport, and simultaneous highly catalytic oxidizability presents an enticing alternative for industrialized water treatment. Herein, a kind of cerium oxide (CeO2) loaded layered double hydroxide (LDH) composites that was fabricated by seeds embedded epitaxial growth based on hydrothermal method anchored on a three-dimensional porous polyvinylidene fluoride (PVDF) framework (denoted as CeO2@LDH-PVDF) and function as an efficient catalytic activator for peroxymonosulfate (PMS) activation. This module features as lamellar LDH nano-flowers not only in situ anchoring onto both sides of the PVDF surface but also along the wall of the pores in an ab-plane vertically interlaced growth pattern. A packed tower device suitable for the catalytic module is also proposed as proof of concept for consecutive pollutants disposal. This module exhibits dual functions of filtration and oxidation, demonstrating a promising removal efficiency for tetracycline (95.8%, 30 mg/L) in conjunction with PMS. Accurate operation parameters are obtained by using the response surface methodology to further reduce the energy consumption (CeO2 containing: 9.03%, PMS concentration: 0.798 mM; pH: 6.513). Encouragingly, the CeO2@LDH-PVDF is not only capable of achieving ultrafast removal in flowing various contaminants, but also reveals wide practical applicability in tap water and reservoir. Moreover, it provides evidence that the binding force between LDH and PVDF is enhanced by virtue of the unique “Mortise-Tenon” structure, which is conducive to maintaining the catalytic activity. Furthermore, the formation of a complex of M−(HO)OSO3− and the succeeding redox cycle of Ni2+/Ni3+, Fe2+/Fe3+, Co2+/Co3+ explain the generation of reactive radicals in PMS activation. Moreover, a new redox cycle of Ce3+/Ce4+ promotes the utilization efficiency of PMS. Three possible tetracycline degradation pathways are proposed and the toxicity of the by-products is reduced. Finally, the module possesses an ideal universality, good cycling stability, favorable antifouling performance, and superior renewability. It is predicted to be integrated with multiple mature technologies to conduct industrial water treatment due to its changeable shape and durability.

Improving conventional household greensand treatment for efficient Mn(II) removal from drinking water

Geogenic contaminants pose a global threat to ensuring access to safe drinking water. Manganese (Mn) is a naturally-occurring redox-active element which in its reduced form, Mn(II), is a widespread groundwater contaminant. Prolonged consumption of water containing high levels of Mn has been linked to adverse effects on memory, attention, motor skills, and nervous system function, particularly in vulnerable groups including pregnant individuals and young children. In addition, Mn can lead to aesthetic issues such as altered taste, clogging, and damage to plumbing systems. While Mn has historically been regulated as an aesthetic concern, a mounting body of evidence linking health issues to Mn exposure through drinking water has heightened the challenges of using groundwater to meet drinking water needs. Recently, Health Canada established a health guideline which set a maximum acceptable concentration for total Mn in drinking water of 120 μg/L. Greensand (GS) filters are commonly used in conventional drinking water treatment systems for Mn(II) removal due to their cost-effectiveness and high exchange capacity. However, under certain conditions conventional GS systems may have a low Mn(II) removal efficiency (Galangashi et al. 2021) and encounter challenges related to Mn leaching (Outram et al. 2018), resulting in failure to meet health-related standards. Furthermore, GS filters typically undergo regeneration using potassium permanganate (KMnO4), a mild oxidant that results in the release of additional Mn waste byproducts during the regeneration of the filter. Recent research suggests that Mn-containing materials can effectively activate peroxymonosulfate (PMS) and produce reactive oxygen species (ROS) that facilitate contaminant degradation. This study aims to investigate whether PMS may be used to improve greensand treatment systems and enhance Mn(II) removal from drinking water. Batch experiments were performed to test the Mn(II) removal efficiency across a range of PMS concentrations (0-500 μM) and GS mass (0.1-3 g). Aqueous Mn concentrations were measured over time using inductively coupled plasma optical emission spectrometry (ICP-OES). Solid-phase reaction products were characterized by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The mechanisms of Mn oxidation were identified by quenching experiments and electron paramagnetic resonance (EPR) spectroscopy. The activation of PMS by greensand significantly increased the removal efficiency of Mn(II) compared to the conventional method (e.g., 96.83(±3.77)% at PMS = 500 µM vs. 5.77(±11.1)% at PMS = 0 µM). Our results attribute the mechanism underlying increased Mn removal in our improved treatment method to advanced oxidation processes that involve free radicals (e.g., hydroxyl radical (·OH) and sulfate radical (SO4·-)) and non-free radical pathways, with Mn oxides as the main oxidation products. This study provides a new treatment method for more efficient Mn(II) removal while simultaneously reducing Mn wastes produced during the regeneration cycle which allows for a more sustainable and holistic management of invaluable groundwater resources.

A novel catalytic filtration process using MnO2@sand and peroxymonosulfate for unselective removal of organic contaminants from water

Multiple catalytic oxidation processes involving new synthesized materials have recently been examined to replace conventional oxidative treatment methods for water purification, but upscaling and demonstration stages are mostly lacking, which hinders their practical implementation. In this study, we introduce a novel catalytic process where peroxymonosulfate (PMS) is activated by MnO2 surfaces that are attached on natural sand as part of a catalytic filtration column (CFC). PMS decomposition in the CFC was stable during steady-state filter operation with different natural waters (tap water and secondary effluent) and sulfate radicals were identified as main radical species. Complete oxidation (>99 %) of 10 mg/L rhodamine B in tap water could be achieved with PMS concentrations as low as 0.2 mM and a residence time of less than 3 min. Furthermore, unselective oxidation of various recalcitrant and environmentally-relevant trace organic chemicals (e.g., carbamazepine, sulfamethoxazole, and benzotriazole) was achieved with 0.6 mM PMS in tap water and secondary effluent, proving the robustness of the process in presence of multiple organic and inorganic constituents. Future investigations are needed to optimize the CFC process for specific applications and confirm its operation in real-world water matrices and to study sustainability aspects. Overall, this study demonstrates the potential of the CFC process to be implemented as a practical nano-enabled water treatment and offers a framework for next steps to be taken before upscaling. It provides important performance data that can be used as reference for future proposals of scalable catalytic oxidation water treatment technology.

Construction of CuMoO4/MnO2/tourmaline composite for efficient organic wastewater decontamination via photo-Fenton-like processes

A CuMoO4/MnO2/tourmaline (CMT) heterogeneous photocatalyst was successfully constructed by hydrothermal method followed by calcination and applied to activate peroxymonosulfate (PMS) for organic contaminant degradation over a wide pH range under visible light illumination. The CMT catalyst exhibited impressive degradation efficiencies of tetracycline hydrochloride (TC, 93.48%), safranine T (SaT, 100%), acridine orange (AO, 99.46%), methyl orange (MO, 97.47%), neutral red (NR, 94.10%), trypan blue (TB, 93.67%), methylene blue (MB, 90.36%) and rhodamine B (RhB, 89.85%) within 50 min. The influence of related parameters including catalyst dosage, PMS concentration, initial pH value, TC concentration, coexisting ions, humic acid (HA) and different water matrices on TC degradation were systematically investigated. According to quenching experiments and electron paramagnetic resonance (EPR) tests, e−, SO4•−, •OH, •O2− and 1O2 all contributed to TC degradation, and •O2− played a predominant role in the photo-Fenton-like process. The reusability of CMT was evaluated by consecutive experiments, and comparable removal efficiencies could be maintained after five cycles. The degradation pathways of TC were deduced and the toxicity of degradation intermediates based on HPLC−MS detection was estimated by Toxicity Estimation Software (T.E.S.T.). Moreover, the catalytic degradation mechanisms of TC in CMT/PMS/Vis system were further proposed and the role of tourmaline was illustrated. This work opens an avenue for the construction of heterogeneous catalysts based on natural minerals in PMS/Vis coupling system for wastewater decontamination.

Visible light-driven Z-scheme Bi2O3/CuBi2O4 heterojunction with dual metal ions cycle for PMS activation and Lev degradation

In this study, Bi2O3/CuBi2O4 composite was prepared by sol–gel method, which was used to degrade levofloxacin (Lev) by the synergistic effect of visible light and peroxymonosulfate (PMS). The physicochemical properties of Bi2O3/CuBi2O4 were regulated by varying the molar ratio of the raw materials. The structure and morphology of the materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and ultraviolet–visible diffuse reflectance spectroscopy (UV–Vis DRS). Secondly, Bi2O3/CuBi2O4/Vis/PMS system was constructed to investigate the effects of different conditions (pollutant concentration, catalyst dosage, PMS concentration, pH and different anion concentration) on the removal effect of Lev. Benefit from the highly ordered alternating nanoparticles and nanosheets, Bi2O3/CuBi2O4 showed satisfactory PMS activation ability than single Bi2O3. The degradation rate increased from 12.98 ± 2.41% (Bi2O3) to 70.62 ± 0.07% (Bi2O3/CuBi2O4) within 120 min. Finally, the quenching experiments and electron paramagnetic resonance (EPR) results showed that radical pathways (h+, SO4-·, ·OH) and non-radical pathways (1O2) were both involved in the PMS activation process. The main reaction mechanism of Bi2O3/CuBi2O4/Vis/PMS system was predicted, the unique electron transfer pathway of Z-scheme heterojunction and Cu(II)/Cu(I), Bi(V)/Bi(III) redox-cycle on the catalyst surface effectively drove the generation of radicals, realizing the high efficiency of pollutant degradation.

Exploration for cobalt/nitrogen-doped catalyst to creatinine degradation via peroxymonosulfate activation: toxicity evaluation, statistical modeling, and mechanisms study.

Developing multifunctional catalysts applied in diversiform modes via advanced oxidation processes (AOPs) is a promising and attractive approach for organic pollution degradation. Herein, a novel hollow bamboo-like structural cobalt/nitrogen-doped carbonized material (CoC/N) was employed as a catalyst for AOPs, in which CoC/N was prepared in situ through calcining a Co-based coordination polymer. When CoC/N was utilized as a peroxymonosulfate (PMS) activator, the catalyst stood out prominent activities for effective CA oxidation. Furthermore, a five-level central composite rotatable design (CCRD) model describing CA decay as a function of PMS concentration, CoC/N dosage, and solution pH value was successfully constructed and engaged to explore the optimal operating conditions. Finally, the possible degradation mechanism of CA in CoC/N-PMS system was proposed by quantum chemistry calculation and LC/MS analysis. This work shed light on the structural morphology of the catalyst and its PMS synergy degradation pathway, which promotes its applications in miscellaneous pollutant degradation. A new Co/N-doped material was used to degrade unconventionality organic pollutant creatinine (CA) for the first time, in which the scientific approaches of five-level central composite rotatable design (CCRD) model, response surface methodology (RSM) and density function theory (DFT) were employed to evaluate the material performance and CA degradation pathway. The toxicity evaluation, statistical modeling and mechanisms study have been investigated meticulously.

Enhanced peroxymonosulfate activation via heteroatomic doping defects of pyridinic and pyrrolic N in 2D N‑doped carbon nanosheets for BPA degradation

Understanding the role of intrinsic defects and nonmetallic heteroatom doping defects in activating peroxymonosulfate (PMS) and subsequently degrading endocrine-disrupting compounds is crucial for designing more efficient carbon catalysts. Therefore, we synthesized N-rich carbon nanosheets (NCs) through pyrolysis of a glutamic acid and melamine mixture and utilized them to activate PMS for bisphenol A (BPA) degradation. Different weight ratios of the above mixtures were allowed for manipulating NCs' defect level and N configuration. The reaction rate constant (k) was significantly positively correlated with the pyridinic and pyrrolic N content, and negatively and weakly positively correlated with graphite N and intrinsic defects, respectively. These findings suggest pyridinic and pyrrolic N, rather than graphitic N and intrinsic defects, enhance PMS activation to generate reactive oxygen species (specifically O•–2 and 1O2) and oxidize BPA. The NC-activated PMS system with the highest N content (17.9 atom%) demonstrated a remarkably high k (0.127 min−1) using minimal concentrations of PMS (0.4 mM) and NC (0.15 g/L), highlighting the system's efficiency. Excess halide anions led to significantly increased k with only a limited formation of trichloromethane (disinfection byproducts) in presence of 100 mM Cl−. This study offers novel perspectives on identifying catalytic sites within N-doped carbonaceous materials.

Heterogeneous activation of peroxymonosulfate by recyclable magnetic CuO/Fe3O4 nanosheets for efficient degradation of organic pollutants

In this work, recyclable magnetic CuO/Fe3O4 nanosheetswere successfully synthesized via a simple continuous precipitation method, which can effectively activate peroxymonosulfate (PMS) to decompose organic pollutants. The properties of CuO/Fe3O4 nanosheets were measured by a series of characterization techniques. CuO/Fe3O4 composites showed highly effectiveness for PMS activation to degrade methyl blue (MB), and several influencing factors were investigated, such as initial pH, catalyst dosage, PMS concentration and reaction temperature. Although CuO/Fe3O4/PMS system exhibited effectiveness for MB degradation in a wide pH range, the natural pH value was the best. The increase in reaction temperature is favorable for MB degradation, and the activation energy was calculated as 40.34 kJ/mol. Quenching experiments and electron spin resonance (ESR) analysis proved that OH, SO4- and 1O2 were generated in the CuO/Fe3O4/PMS system, and SO4- and 1O2 played the dominant role. Moreover, CuO/Fe3O4 remained good activity and stability after being recycled five times. In addition, the complete degradation of methylene orange (MO) and tetracycline hydrochloride (TC), and MB degradation in tap water and lake water further confirmed the wide applicability of the CuO/Fe3O4/PMS system. These results exhibited that CuO/Fe3O4/PMS system has great advantages of high removal efficiency, reusability and wide applicability, demonstrating its potential environmental application in the treatment of organic wastewater.

Dual Activation of Peroxymonosulfate Using MnFe2O4/g-C3N4 and Visible Light for the Efficient Degradation of Steroid Hormones: Performance, Mechanisms, and Environmental Impacts.

Single activation of peroxymonosulfate (PMS) in a homogeneous system is sometimes insufficient for producing reactive oxygen species (ROS) for water treatment applications. In this work, manganese spinel ferrite and graphitic carbon nitride (MnFe2O4/g-C3N4; MnF) were successfully used as an activator for PMS under visible light irradiation to remove the four-most-detected-hormone-contaminated water under different environmental conditions. The incorporation of g-C3N4 in the nanocomposites led to material enhancements, including increased crystallinity, reduced particle agglomeration, amplified magnetism, improved recyclability, and increased active surface area, thereby facilitating the PMS activation and electron transfer processes. The dominant active radical species included singlet oxygen (1O2) and superoxide anions (O2•-), which were more susceptible to the estrogen molecular structure than testosterone due to the higher electron-rich moieties. The self-scavenging effect occurred at high PMS concentrations, whereas elevated constituent ion concentrations can be both inhibitors and promoters due to the generation of secondary radicals. The MnF/PMS/vis system degradation byproducts and possible pathways of 17β-estradiol and 17α-methyltestosterone were identified. The impact of hormone-treated water on Oryza sativa L. seed germination, shoot length, and root length was found to be lower than that of untreated water. However, the viability of both ELT3 and Sertoli TM4 cells was affected only at higher water compositions. Our results confirmed that MnF and visible light could be potential PMS activators due to their superior degradation performance and ability to produce safer treated water.